How to obtain the file extension using PHP

How to obtain the file extension using PHP

There are many methods for PHP to get the file extension. The following three methods are provided. You can study these methods without explaining them and give the final correct answer.

Echo pathinfo ('/www/htdocs/your_image.jpg', PATHINFO_EXTENSION );
Incorrect syntax:
You may write

Function get_file_extension ($ file_name ){
Return substr (strrchr ($ file_name, '.'), 1 );
}
Or write it like this

Function file_extension ($ filename ){
Return end (explode (".", $ filename ));
}
What does pathinfo do?

<? Php tutorial
$ File_path = pathinfo ('/www/htdocs/your_image.jpg ');
 
Echo "$ file_path ['dirname'] n ";
Echo "$ file_path ['basename'] n ";
Echo "$ file_path ['extension'] n ";
Echo "$ file_path ['filename'] n"; // only in PHP 5.2 +
?>
The above output

/Www/htdocs
Your_image.jpg
Jpg
Your_image

The Code is as follows:
<? Php
// Method 1
Function extend_1 ($ file_name)
{
$ Retval = "";
$ Pt = strrpos ($ file_name ,".");
If ($ pt) $ retval = substr ($ file_name, $ pt + 1, strlen ($ file_name)-$ pt );
Return ($ retval );
}
// Method 2
Function extend_2 ($ file_name)
{
$ Extend = pathinfo ($ file_name );
$ Extend = strtolower ($ extend ["extension"]);
Return $ extend;
}
// Method 3
Function extend_3 ($ file_name)
{
$ Extend = explode (".", $ file_name );
$ Va = count ($ extend)-1;
Return $ extend [$ va];
}
?>